Methods for increasing the refractive index of high-index nanoimprint lithography films

ABSTRACT

Embodiments of the present disclosure generally relate to optically densified nanoimprint films and processes for making these optically densified nanoimprint films, as well as optical devices containing the optically densified nanoimprint films. In one or more embodiments, a method of forming a nanoimprint film includes positioning a substrate containing a porous nanoimprint film within a processing chamber, where the porous nanoimprint film contains nanoparticles and voids between the nanoparticles, and the porous nanoimprint film has a refractive index of less than 2. The method also includes depositing a metal oxide on the porous nanoimprint film and within at least a portion of the voids to produce an optically densified nanoimprint film during an atomic layer deposition (ALD) process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit to U.S. Prov. Appl. No. 63/012,688,filed on Apr. 20, 2020, and U.S. Prov. Appl. No. 63/012,691, filed onApr. 20, 2020, which are herein incorporated by reference.

BACKGROUND Field

Embodiments of the present disclosure generally relate to micro-deviceprocessing, and more specifically to nanoimprint lithography (NIL) filmsand processes to make the same.

Description of the Related Art

Nano and micro-patterning of nanoparticle imprint provides opportunitiesfor developing nanomaterial-based optics, electronics, displays, energydevices, sensors, and other types of devices with nanometer scaleresolution. The imprint materials currently available contain eitherorganic (high index polymers) or inorganic-organic hybrid materials(sol-gel). The majority of the imprint materials have low refractiveindex (<1.7), along with multiple problems associated with opticaltransparency in visible region, optical resolution, processability, highshrinkage of imprinted features and cost effectiveness. In addition,many of the imprint materials have relatively low hardness, fracturestrain, yield strength, and/or etch resistance, which if increased,would be beneficial. Some imprint materials have relatively high modulusof elasticity, which if decreased, would also be beneficial.

Therefore, improved nanoimprint films with a beneficial physicalproperties and related processes for making these nanoimprint films areneeded.

SUMMARY

Embodiments of the present disclosure generally relate to densifiednanoimprint films and related processes for making these densifiednanoimprint films. The densified nanoimprint films are typically alsooptically densified nanoimprint films relative to the base or porousnanoimprint film from which they are formed. The densified nanoimprintfilms can be useful as nanoimprint lithography (NIL) films. Thedensified nanoimprint films and/or optically densified nanoimprint filmstypically have a relatively high refractive index (>1.9 or >2), as wellas relatively high hardness, fracture strain, yield strength, and/oretch resistance (e.g., reduced etch rate), and also relatively lowmodulus of elasticity.

In one or more embodiments, a method of forming a nanoimprint filmincludes positioning a substrate containing a porous nanoimprint filmwithin a processing chamber, where the porous nanoimprint film containsnanoparticles and voids between the nanoparticles, and the porousnanoimprint film has a refractive index of less than 2. The method alsoincludes depositing a metal oxide on the porous nanoimprint film andwithin at least a portion of the voids to produce an optically densifiednanoimprint film during an atomic layer deposition (ALD) process.

In some embodiments, a method of forming a nanoimprint film includesdisposing an imprint composition containing nanoparticles on asubstrate, contacting the imprint composition with a stamp having apattern, converting the imprint composition to a porous nanoimprintfilm, and removing the stamp from the porous nanoimprint film. Themethod also includes positioning the substrate containing the porousnanoimprint film within a processing chamber, where the porousnanoimprint film contains nanoparticles and voids between thenanoparticles, and the porous nanoimprint film has a refractive index ofless than 2. The method further includes depositing a metal oxide on theporous nanoimprint film and within at least a portion of the voids toproduce an optically densified nanoimprint film during an ALD process,where the optically densified nanoimprint film has a refractive indexgreater than the refractive index of the porous nanoimprint film.

In other embodiments, an optically densified nanoimprint film contains abase nanoimprint film having nanoparticles and voids between thenanoparticles, and where the base nanoimprint film has a refractiveindex of less than 2. The optically densified nanoimprint film alsocontains a metal oxide disposed on the base nanoimprint film andcontained within at least a portion of the voids. The metal oxideincreases the refractive index of the base nanoimprint film.

In one or more embodiments, an optical device with gratings containingan optically densified nanoimprint film is provided and discussedherein. Any of the optically densified nanoimprint films and/or methodsfor producing optically densified nanoimprint films described anddiscussed herein can be used to produce the optical device. For example,the optically densified nanoimprint film contains a base nanoimprintfilm and a metal oxide disposed on the base nanoimprint film and inbetween the nanoparticles, where the base nanoimprint film has arefractive index of less than 2, as described and discussed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlyexemplary embodiments and are therefore not to be considered limiting ofits scope, may admit to other equally effective embodiments.

FIGS. 1A-1F depict cross-sectional views of a workpiece being processedthrough multiple operations while preparing a nanoimprint filmcontaining nanoparticles, according to one or more embodiments describedand discussed herein.

FIGS. 2A-2B depict cross-sectional views of a workpiece being processedto prepare an optically densified nanoimprint film, according to one ormore embodiments described and discussed herein.

FIG. 3 depicts a front view of an optical device, according to one ormore embodiments described and discussed herein.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe Figures. It is contemplated that elements and features of one ormore embodiments may be beneficially incorporated in other embodiments.

DETAILED DESCRIPTION

In one or more embodiments, a method of forming a nanoimprint filmincludes positioning a substrate containing a base or porous nanoimprintfilm within a processing chamber, where the porous nanoimprint filmcontains nanoparticles and voids between the nanoparticles, and theporous nanoimprint film has a refractive index of less than 2. Thevoids, such as the spaces disposed between the nanoparticles, cancontain ambient air, residual organic materials (e.g., one or morehydrocarbons and/or other organic compounds), particulates, and/or oneor more other contaminants which can have a relatively low refractiveindex, such as from about 1, about 1.2, or about 1.3 to about 1.4 orabout 1.5.

The method also includes depositing one or more metal oxides on theporous nanoimprint film and within at least a portion of the voids toproduce an optically densified nanoimprint film during an atomic layerdeposition (ALD) process. The voids can be at least partially filled,substantially filled, or completely filled. For example, at least 3%, atleast 5%, or at least 10% of the volume occupied by the voids is filledwith the metal oxide by the ALD process. In other examples, from about20% to about 90% of the volume occupied by the voids is filled with themetal oxide by the ALD process. In some examples, greater than 90%, suchas about 95% to 100%, of the volume occupied by the voids is filled withthe metal oxide by the ALD process. The optically densified nanoimprintfilm has a refractive index greater than the refractive index of thebase or porous nanoimprint film.

In one or more embodiments, the refractive index of the opticallydensified nanoimprint film is greater than the refractive index of theporous nanoimprint film by about 0.5%, about 0.75%, about 1%, about 2%,about 4%, or about 5% to about 6%, about 8%, about 10%, about 12%, about15%, about 20%, about 25%, about 30%, or more. For example, therefractive index of the optically densified nanoimprint film is about0.5% to about 30% greater than the refractive index of the porousnanoimprint film. In other examples, the refractive index of theoptically densified nanoimprint film is about 0.65% to about 20% greaterthan the refractive index of the porous nanoimprint film. In otherexamples, the refractive index of the optically densified nanoimprintfilm is about 0.75% to about 10% greater than the refractive index ofthe porous nanoimprint film. In some examples, the refractive index ofthe optically densified nanoimprint film is about 1% to about 6% greaterthan the refractive index of the porous nanoimprint film.

The refractive index of the porous nanoimprint film is about 1.50, about1.65, or about 1.75 to about 1.80, about 1.85, about 1.90, about 1.95,about 197, about 1.99, or less than 2. In one or more examples, therefractive index of the porous nanoimprint film is about 1.5 to about1.95 or about 1.75 to about 1.95. The refractive index of the opticallydensified nanoimprint film is greater than the refractive index of theporous nanoimprint film. In some examples, the refractive index of theoptically densified nanoimprint film is about 1.8 or greater. Forexample, the refractive index of the optically densified nanoimprintfilm is about 1.8 to about 2.2, about 1.85 to about 2.15, or about 1.9to about 2.1.

Any densified nanoimprint film and/or optically densified nanoimprintfilm can have an increased mass per unit volume and/or can have anincreased refractive index over the porous nanoimprint film and/or thebase nanoimprint film, as described and discussed herein. In one or moreembodiments, the densified nanoimprint film has a greater value ofhardness, a greater value of fracture strain, a greater value of yieldstrength, and/or a greater value of etch resistance than the porousnanoimprint film or the base nanoimprint film. In some embodiments, thedensified nanoimprint film has a lesser value of modulus of elasticitythan the porous nanoimprint film or the base nanoimprint film.

In one or more embodiments, the nanoparticles can be or include titaniumoxide, zirconium oxide, niobium oxide, tantalum oxide, hafnium oxide,chromium oxide, indium tin oxide, silicon nitride, or any combinationthereof. Any nanoparticle described and discussed here can be used beprepare the porous nanoimprint film. The metal oxide can be or includeone or more aluminum oxide, titanium oxide, zirconium oxide, niobiumoxide, tantalum oxide, indium oxide, indium tin oxide, hafnium oxide,chromium oxide, scandium oxide, tin oxide, zinc oxide, yttrium oxide,praseodymium oxide, magnesium oxide, or any combination thereof. Insteadof a metal oxide or along with a metal oxide, one or more silicon oxidesand or silicon nitrides can be deposited on and/or in the porousnanoimprint film. Exemplary silicon oxides can be or include siliconmonoxide, silicon dioxide, one or more silicon oxide of SiO_(x) (where2>x>1), one or more silicates, silicon nitride, silicon oxynitride, orany combination thereof. The metal oxide can have a refractive indexgreater than, equal to, or less than the refractive index of thenanoparticles and/or the porous nanoimprint film. Even if the refractiveindex of the metal oxide is equal to or less than the refractive indexof the nanoparticles and/or the porous nanoimprint film, the metal oxidehas a greater refractive index than the one or more materials which isbeing replaced in the voids, such as air, organic compounds,particulates, and/or one or more other contaminants.

Methods for Preparing an Imprinted Surface of the Base or PorousNanoimprint Film

In one or more embodiments, methods for preparing an imprinted surface,such as a nanoimprint lithography (NIL) film, are provided. Theimprinted surface is one or more exposed surfaces of the base or porousnanoimprint film described and discussed herein. The method includesdisposing, coating, or otherwise placing an imprint composition on oneor more substrates, contacting the imprint composition with a stamphaving a pattern, converting the imprint composition to an imprintmaterial (e.g., a porous nanoimprint film), and removing the stamp fromthe imprint material. In some examples, the substrate (e.g., wafer) canbe or include glass, quartz, silicon oxide, such as a glass substrate ora glass wafer. In other examples, the substrate can be or includesilicon, silicon-germanium, plastic, and/or other materials. The imprintcomposition and/or material can have a refractive index of about 1.7 toabout 2.0, or about 1.7 to less than 2, such as about 1.9, 1.85, or1.80. The pattern on the stamp and transferred to the imprinted surfacecan be a 1-dimension pattern, a 2-dimension pattern, or a 3-dimensionpattern.

FIGS. 1A-1F depict cross-sectional views of a workpiece being processedthrough multiple operations while preparing a nanoimprint filmcontaining nanoparticles, such as the base or porous nanoimprint film,according to one or more embodiments described and discussed herein. Theporous nanoimprint film is formed on the substrate by an imprintprocess. The imprint process includes disposing an imprint composition104 containing nanoparticles on a substrate 102 and aligning a stamp 120above or adjacent to the imprint composition 104 (FIG. 1A). The imprintcomposition 104 is impressed or otherwise contacted with the stamp 120having a pattern (FIGS. 1B-1C). The imprint composition 104 is convertedto a porous nanoimprint film 106 (FIG. 1D). In some examples, a curingprocess with heat and/or radiation (UV light) is used to convert theimprint composition 104 to the porous nanoimprint film 106. The stamp120 is removed from the porous nanoimprint film 106, which is leftdisposed on the substrate 102 (FIGS. 1E-1F). The pores of the porousnanoimprint film 106 may have some residual organic material, such as aminimal organic matrix that exists because of imperfect packing ofnanoparticles.

In some examples, the imprint composition is disposed on the substrateby spin coating, drop casting, blade coating, and/or other coatingprocesses. The imprint composition is disposed on the substrate as afilm or a layer having a predetermined thickness. The thickness of theimprint composition is about 50 nm, about 80 nm, about 100 nm, about 120nm, about 150 nm, or about 200 nm to about 250 nm, about 300 nm, about400 nm, about 500 nm, about 600 nm, about 800 nm, about 1,000 nm, about1,200 nm, or thicker. For example, the thickness of the imprintcomposition is about 50 nm to about 1,000 nm, about 100 nm to about1,000 nm, about 200 nm to about 1,000 nm, about 400 nm to about 1,000nm, about 500 nm to about 1,000 nm, about 600 nm to about 1,000 nm,about 800 nm to about 1,000 nm, about 50 nm to about 600 nm, about 100nm to about 600 nm, about 200 nm to about 600 nm, about 400 nm to about600 nm, about 500 nm to about 600 nm, about 50 nm to about 400 nm, about100 nm to about 400 nm, about 200 nm to about 400 nm, or about 300 nm toabout 400 nm.

The imprint composition is converted to the imprint material (e.g., theporous nanoimprint film) by exposing the imprint composition to heat,ultraviolet light, infrared light, visible light, microwave radiation,and/or any combination thereof. In one or more examples, when convertingthe imprint composition to the imprint material, the imprint compositionis exposed to a light source having a wavelength of about 300 nm toabout 365 nm. In other examples, when converting the imprint compositionto the imprint material, the imprint composition is exposed to heat andmaintained at a temperature of about 30° C. to about 100° C. for a timeperiod of about 30 seconds to about 1 hour. In some examples, theimprint composition is exposed to heat and maintained at a temperatureof about 50° C. to about 60° C. for a time period of about 1 minute toabout 15 minutes.

ALD of Metal Oxide to Prepare Optically Densified Nanoimprint Film

In one or more embodiments, one or more metal oxides are deposited orotherwise formed by ALD or another vapor deposition process on andwithin the base or porous nanoimprint film. Voids, or portions of voids,within the porous nanoimprint film are at least partially filled withthe metal oxide to produce the optically densified nanoimprint film. Asdiscussed above, the voids can be at least partially filled,substantially filled, or completely filled by the metal oxide during theALD process.

FIGS. 2A-2B depict cross-sectional views of a workpiece being processedto convert a porous nanoimprint film to be an optically densifiednanoimprint film, according to one or more embodiments described anddiscussed herein. The porous nanoimprint film 106 containing features130 is left disposed on the substrate 102, as depicted in FIG. 2A. Theporous nanoimprint film 106 contains a plurality of nanoparticles 108separated by a plurality of spaces or voids 110. An ALD process oranother vapor deposition process is used to deposit metal oxide 112between the nanoparticles 108 and into the voids 110 to produce theoptically densified nanoimprint film 116, as depicted in FIG. 2B. Thefeatures 130 formed in the porous nanoimprint film 106 are at leastsubstantially, if not completely, preserved in the optically densifiednanoimprint film 116.

The ALD process includes sequentially exposing the porous nanoimprintfilm to a metal precursor and an oxidizing agent (and or other reagent)during an ALD cycle to deposit the metal oxide. The ALD cycle alsoincludes exposures of purge gas between each exposure of the precursors.For example, the ALD process includes sequentially exposing the porousnanoimprint film to a metal precursor, a purge gas, an oxidizing agent(and or other reagent), and the purge gas during the ALD cycle. Thepurge gas can be or include nitrogen (N₂), argon, helium, or anycombination thereof.

In some instances, the ALD cycle can be performed a single time todeposit the metal oxide while producing the optically densifiednanoimprint film. In other examples, the ALD cycle can be performed twoor more times to deposit the metal oxide while producing the opticallydensified nanoimprint film. For example, the ALD cycle can be repeatedfrom 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, or 15 times to about 18, about 20,about 25, about 30, about 40, about 50, about 60, about 80, about 100,or more times to deposit the metal oxide while producing the opticallydensified nanoimprint film.

In one or more examples, if the metal oxide is or contains aluminumoxide, then the metal precursor is one or more aluminum precursors, suchas an alkyl aluminum compound, for example, trimethylaluminum,triethylaluminum, tripropylaluminum, tributylaluminum, or the like. Theoxidizing agent can be or include water, oxygen (O₂), ozone, atomicoxygen, nitrous oxide, hydrogen peroxide, one or more organic peroxides,plasma thereof, or any combination thereof.

In one or more embodiments, an optically densified nanoimprint filmcontains a base nanoimprint film containing nanoparticles and optionallyvoids between the nanoparticles, and where the base nanoimprint film hasa refractive index of less than 2. The optically densified nanoimprintfilm also contains a metal oxide disposed on the base nanoimprint filmand contained within at least a portion of the voids. The opticallydensified nanoimprint film has a refractive index greater than therefractive index of the base nanoimprint film.

Imprint Compositions for Preparing NIL Films

Embodiments of the present disclosure generally relate to imprintcompositions and imprint materials (e.g., base or porous nanoimprintfilms) useful for nanoimprint lithography (NIL). The imprint compositioncan be converted to the imprint material by applying heat and/or one ortypes of radiation, such as light or microwave. In one or moreembodiments, the imprint composition contains one or more types ofnanoparticles, one or more surface ligands, one or more solvents, one ormore additives, and one or more acrylates.

Each of the nanoparticles can be a single particle (bare particle) orcan be a coated particle, such as containing a core and one or moreshells disposed around the core. In some examples, the nanoparticles cancontain one or more types of surface ligands coupled to the outersurface of the particle (e.g., ligated NPs or stabilized NPs). Thenanoparticles can have one or more different shapes or geometries, suchas spherical, oval, rod, cubical, wire, cylindrical, rectangular, orcombinations thereof.

The nanoparticle or the core can have a size or a diameter of about 2nm, about 5 nm, about 8 nm, about 10 nm, about 12 nm, about 15 nm, about20 nm, about 25 nm, about 30 nm, or about 35 nm to about 40 nm, about 50nm, about 60 nm, about 80 nm, about 100 nm, about 150 nm, about 200 nm,about 250 nm, about 300 nm, about 400 nm, about 500 nm, or larger. Forexample, the nanoparticle or the core can have a size or a diameter ofabout 2 nm to about 500 nm, about 2 nm to about 300 nm, about 2 nm toabout 200 nm, about 2 nm to about 150 nm, about 2 nm to about 100 nm,about 2 nm to about 80 nm, about 2 nm to about 60 nm, about 2 nm toabout 50 nm, about 2 nm to about 40 nm, about 2 nm to about 30 nm, about2 nm to about 20 nm, about 2 nm to about 15 nm, about 2 nm to about 10nm, about 10 nm to about 500 nm, about 10 nm to about 300 nm, about 10nm to about 200 nm, about 10 nm to about 150 nm, about 10 nm to about100 nm, about 10 nm to about 80 nm, about 10 nm to about 60 nm, about 10nm to about 50 nm, about 10 nm to about 40 nm, about 10 nm to about 30nm, about 10 nm to about 20 nm, about 10 nm to about 15 nm, about 50 nmto about 500 nm, about 50 nm to about 300 nm, about 50 nm to about 200nm, about 50 nm to about 150 nm, about 50 nm to about 100 nm, about 50nm to about 80 nm, or about 50 nm to about 60 nm.

The nanoparticle can be or contain one or more metal oxides, one or morenon-metal oxides, one or more non-metal nitrides, and/or diamondmaterials. The nanoparticle can contain titanium oxide, zirconium oxide,niobium oxide, tantalum oxide, hafnium oxide, chromium oxide, indium tinoxide, silicon nitride, diamond, or any combination thereof. In someembodiments, if the nanoparticle one or more shells disposed around thecore, the core and shell can be the same material or differentmaterials. In one or more examples, the core contains titanium oxide andthe shell contains silicon oxide, zirconium oxide, niobium oxide, or anycombination thereof. In other examples, the core contains niobium oxideand the shell contains silicon oxide, zirconium oxide, or anycombination thereof. In some examples, the core contains zirconium oxideand the shell contains silicon oxide.

In some examples, the core has a diameter of about 2 nm to about 500 nmand the shell has a thickness of about 0.1 nm to about 100 nm. In otherexamples, the core has a diameter of about 5 nm to about 200 nm and theshell has a thickness of about 0.5 nm to about 60 nm. In some examples,the core has a diameter of about 10 nm to about 100 nm and the shell hasa thickness of about 1 nm to about 15 nm.

In one or more embodiments, the imprint composition contains about 0.1wt %, about 0.5 wt %, about 1 wt %, about 2 wt %, about 3 wt %, about 5wt %, about 6 wt %, about 8 wt %, or about 10 wt % to about 12 wt %,about 15 wt %, about 18 wt %, about 20 wt %, about 22 wt %, about 24 wt%, about 25 wt %, about 28 wt %, about 30 wt %, about 32 wt %, about 35wt %, about 38 wt %, or about 40 wt % of the nanoparticles. For example,the imprint composition contains about 0.1 wt % to about 40 wt %, about0.5 wt % to about 40 wt %, about 0.5 wt % to about 35 wt %, about 0.5 wt% to about 32 wt %, about 0.5 wt % to about 30 wt %, about 0.5 wt % toabout 28 wt %, about 0.5 wt % to about 25 wt %, about 0.5 wt % to about22 wt %, about 0.5 wt % to about 20 wt %, about 0.5 wt % to about 18 wt%, about 0.5 wt % to about 15 wt %, about 0.5 wt % to about 12 wt %,about 0.5 wt % to about 10 wt %, about 0.5 wt % to about 8 wt %, about0.5 wt % to about 6 wt %, about 0.5 wt % to about 5 wt %, about 0.5 wt %to about 4 wt %, about 0.5 wt % to about 3 wt %, about 0.5 wt % to about2 wt %, about 0.5 wt % to about 1.5 wt %, about 0.5 wt % to about 1 wt%, about 2 wt % to about 40 wt %, about 2 wt % to about 35 wt %, about 2wt % to about 32 wt %, about 2 wt % to about 30 wt %, about 2 wt % toabout 28 wt %, about 2 wt % to about 25 wt %, about 2 wt % to about 22wt %, about 2 wt % to about 20 wt %, about 2 wt % to about 18 wt %,about 2 wt % to about 15 wt %, about 2 wt % to about 12 wt %, about 2 wt% to about 10 wt %, about 2 wt % to about 8 wt %, about 2 wt % to about6 wt %, about 2 wt % to about 5 wt %, about 2 wt % to about 4 wt %,about 2 wt % to about 3 wt %, about 5 wt % to about 40 wt %, about 5 wt% to about 35 wt %, about 5 wt % to about 32 wt %, about 5 wt % to about30 wt %, about 5 wt % to about 28 wt %, about 5 wt % to about 25 wt %,about 5 wt % to about 22 wt %, about 5 wt % to about 20 wt %, about 5 wt% to about 18 wt %, about 5 wt % to about 15 wt %, about 5 wt % to about12 wt %, about 5 wt % to about 10 wt %, about 5 wt % to about 8 wt %, orabout 5 wt % to about 6 wt % of the nanoparticles.

In other embodiments, the imprint composition contains about 40 wt %,about 50 wt %, about 55 wt %, about 60 wt %, about 62 wt %, or about 65wt % to about 68 wt %, about 70 wt %, about 75 wt %, about 80 wt %,about 85 wt %, about 88 wt %, about 90 wt %, about 92 wt %, about 93 wt%, about 94 wt %, about 95 wt %, about 96 wt %, about 97 wt %, about 98wt %, or more of the nanoparticles. For example, the imprint compositioncontains about 40 wt % to about 98 wt %, about 50 wt % to about 95 wt %,about 50 wt % to about 90 wt %, about 50 wt % to about 80 wt %, about 50wt % to about 75 wt %, about 50 wt % to about 70 wt %, about 50 wt % toabout 65 wt %, about 50 wt % to about 60 wt %, about 50 wt % to about 55wt %, about 60 wt % to about 95 wt %, about 60 wt % to about 90 wt %,about 60 wt % to about 80 wt %, about 60 wt % to about 75 wt %, about 60wt % to about 70 wt %, about 60 wt % to about 65 wt %, about 70 wt % toabout 95 wt %, about 70 wt % to about 90 wt %, about 70 wt % to about 80wt %, or about 70 wt % to about 75 wt % of the nanoparticles.

The surface ligand can be or include one or more carboxylic acids, oneor more esters, one or more amines, one or more alcohols, one or moresilanes, salts thereof, complexes thereof, or any combination thereof.Exemplary surface ligands can be or include oleic acid, stearic acid,propionic acid, benzoic acid, palmitic acid, myristic acid, methylamine,oleylamine, butylamine, benzyl alcohol, oleyl alcohol, butanol, octanol,dodecanol, octeyltriethoxy silane, octeyltrimethoxy silane,3-(trimethoxysilyl)propyl methacrylate, propyltriethoxy silane, saltsthereof, esters thereof, complexes thereof, or any combination thereof.In some example, the surface ligand is at a concentration of about 8 wt% to about 50 wt %, based on the weight of the nanoparticles.

The imprint composition contains about 0.5 wt %, about 1 wt %, about 2wt %, about 3 wt %, about 5 wt %, about 7 wt %, about 8 wt %, or about10 wt % to about 12 wt %, about 15 wt %, about 18 wt %, about 20 wt %,about 25 wt %, about 30 wt %, about 35 wt %, about 40 wt %, about 45 wt%, or about 50 wt % of the surface ligand. For example, the imprintcomposition contains about 0.5 wt % to about 50 wt %, about 1 wt % toabout 50 wt %, about 3 wt % to about 50 wt %, about 5 wt % to about 50wt %, about 5 wt % to about 40 wt %, about 5 wt % to about 35 wt %,about 5 wt % to about 30 wt %, about 5 wt % to about 25 wt %, about 5 wt% to about 20 wt %, about 5 wt % to about 15 wt %, about 5 wt % to about10 wt %, about 10 wt % to about 50 wt %, about 10 wt % to about 40 wt %,about 10 wt % to about 35 wt %, about 10 wt % to about 30 wt %, about 10wt % to about 25 wt %, about 10 wt % to about 20 wt %, about 10 wt % toabout 15 wt %, about 15 wt % to about 50 wt %, about 15 wt % to about 40wt %, about 15 wt % to about 35 wt %, about 15 wt % to about 30 wt %,about 15 wt % to about 25 wt %, or about 15 wt % to about 20 wt % of thesurface ligand.

The solvent can be or include one or more nanoparticle dispersionsolvents, one or more imprinting solvents, other types of solvents, orany combination thereof. The nanoparticle dispersion solvent can be orinclude one or more glycol ethers, alcohols, acetates, esters thereof,salts thereof, derivatives thereof, or any combination thereof. In someexamples, the nanoparticle dispersion solvent can be or include one ormore p-series glycol ethers, one or more e-series glycol ethers, or anycombination thereof. In one or more examples, the nanoparticledispersion solvent contains propylene glycol methyl ether acetate(PGMEA). The imprinting solvent can be or include one or more alcohols,one or more esters, salts thereof, or any combination thereof. In one ormore examples, the imprinting solvent contains ethyl lactate.

In one or more embodiments, the imprint composition contains about 50 wt%, about 55 wt %, about 60 wt %, about 62 wt %, about 65 wt %, about 68wt %, about 70 wt %, about 72 wt %, about 75 wt %, or about 80 wt % toabout 83 wt %, about 85 wt %, about 87 wt %, about 88 wt %, about 90 wt%, about 92 wt %, about 94 wt %, about 95 wt %, about 97 wt %, or about98 wt % of one or more solvents. For example, the imprint compositioncontains about 50 wt % to about 98 wt %, about 60 wt % to about 98 wt %,about 60 wt % to about 95 wt %, about 60 wt % to about 90 wt %, about 60wt % to about 88 wt %, about 60 wt % to about 85 wt %, about 60 wt % toabout 83 wt %, about 60 wt % to about 80 wt %, about 60 wt % to about 78wt %, about 60 wt % to about 75 wt %, about 60 wt % to about 72 wt %,about 60 wt % to about 70 wt %, about 60 wt % to about 68 wt %, about 60wt % to about 65 wt %, about 60 wt % to about 63 wt %, about 70 wt % toabout 98 wt %, about 70 wt % to about 95 wt %, about 70 wt % to about 90wt %, about 70 wt % to about 88 wt %, about 70 wt % to about 85 wt %,about 70 wt % to about 83 wt %, about 70 wt % to about 80 wt %, about 70wt % to about 78 wt %, about 70 wt % to about 75 wt %, about 70 wt % toabout 72 wt %, about 80 wt % to about 98 wt %, about 80 wt % to about 95wt %, about 80 wt % to about 90 wt %, about 80 wt % to about 88 wt %,about 80 wt % to about 85 wt %, about 80 wt % to about 83 wt %, or about80 wt % to about 82 wt % of one or more solvents.

In some embodiments, the imprint composition contains about 0.5 wt %,about 0.8 wt %, about 1 wt %, about 1.5 wt %, about 2 wt %, about 2.5 wt%, about 3 wt %, about 3.5 wt %, about 4 wt %, about 5 wt %, or about 6wt % to about 7 wt %, about 8 wt %, about 10 wt %, about 12 wt %, about14 wt %, about 15 wt %, about 18 wt %, about 20 wt %, or about 25 wt %of the nanoparticle dispersion solvent. For example, the imprintcomposition contains about 0.5 wt % to about 20 wt %, about 1 wt % toabout 20 wt %, about 1 wt % to about 18 wt %, about 1 wt % to about 15wt %, about 1 wt % to about 13 wt %, about 1 wt % to about 12 wt %,about 1 wt % to about 11 wt %, about 1 wt % to about 10 wt %, about 1 wt% to about 8 wt %, about 1 wt % to about 7 wt %, about 1 wt % to about 6wt %, about 1 wt % to about 5 wt %, about 1 wt % to about 4 wt %, about1 wt % to about 3 wt %, about 5 wt % to about 20 wt %, about 5 wt % toabout 18 wt %, about 5 wt % to about 15 wt %, about 5 wt % to about 13wt %, about 5 wt % to about 12 wt %, about 5 wt % to about 11 wt %,about 5 wt % to about 10 wt %, about 5 wt % to about 8 wt %, about 5 wt% to about 7 wt %, about 5 wt % to about 6 wt %, about 8 wt % to about20 wt %, about 8 wt % to about 18 wt %, about 8 wt % to about 15 wt %,about 8 wt % to about 13 wt %, about 8 wt % to about 12 wt %, about 8 wt% to about 11 wt %, about 8 wt % to about 10 wt %, or about 8 wt % toabout 9 wt % of the nanoparticle dispersion solvent.

In other embodiments, the imprint composition contains about 50 wt %,about 55 wt %, about 60 wt %, about 62 wt %, about 65 wt %, about 68 wt%, or about 70 wt % to about 72 wt %, about 75 wt %, about 78 wt %,about 80 wt %, about 82 wt %, about 83 wt %, about 85 wt %, about 87 wt%, about 88 wt %, about 90 wt %, or about 95 wt % of the imprintingsolvent. For example, the imprint composition contains about 50 wt % toabout 95 wt %, about 60 wt % to about 95 wt %, about 60 wt % to about 90wt %, about 60 wt % to about 88 wt %, about 60 wt % to about 85 wt %,about 60 wt % to about 83 wt %, about 60 wt % to about 80 wt %, about 60wt % to about 78 wt %, about 60 wt % to about 75 wt %, about 60 wt % toabout 72 wt %, about 60 wt % to about 70 wt %, about 60 wt % to about 68wt %, about 60 wt % to about 65 wt %, about 60 wt % to about 63 wt %,about 70 wt % to about 98 wt %, about 70 wt % to about 95 wt %, about 70wt % to about 90 wt %, about 70 wt % to about 88 wt %, about 70 wt % toabout 85 wt %, about 70 wt % to about 83 wt %, about 70 wt % to about 80wt %, about 70 wt % to about 78 wt %, about 70 wt % to about 75 wt %,about 70 wt % to about 72 wt %, about 75 wt % to about 98 wt %, about 75wt % to about 95 wt %, about 75 wt % to about 90 wt %, about 75 wt % toabout 88 wt %, about 75 wt % to about 85 wt %, about 75 wt % to about 83wt %, about 75 wt % to about 80 wt %, or about 75 wt % to about 78 wt %of the imprinting solvent.

The additive can be or include one or more perfluoroalkyl ethers, one ormore polyglycols, one or more fatty acids, one or more silanes, one ormore siloxanes, or any combination thereof. Exemplary additives can beor include fluorosurfactant, fluoro-additive, and/or fluorocarbon (e.g.,CAPSTONE® FS-66 or FS-68 fluorosurfactant, available from DuPont),glycolic acid ethoxylate oleyl ether, polyethylene glycol, polypropyleneglycol, lauric acid, myristic acid, stearic acid, palmitic acid,dimethyldiethoxysilane, polydimethylsiloxane, polydiphenylsiloxane,hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, silanolterminated polydimethylsiloxane, vinyl terminated polydimethylsiloxane,1,2-propanediol, salts thereof, esters thereof, complexes thereof, orany combination thereof. The additive can be or include one or morediols, one or more alcohols with three or more alcohol groups, or anycombination thereof. In one or more examples, the additive contains1,2-propanediol. In some examples, the additive is at a concentration ofabout 0.01 wt % to about 2.5 wt %, based on the weight of thenanoparticles.

The imprint composition contains about 0.01 wt %, about 0.05 wt %, about0.1 wt %, about 0.2 wt %, about 0.3 wt %, about 0.5 wt %, about 0.8 wt%, or about 1 wt % to about 1.2 wt %, about 1.5 wt %, about 1.8 wt %,about 2 wt %, about 2.5 wt %, about 3 wt %, about 3.5 wt %, about 4 wt%, about 5 wt %, about 6 wt %, about 8 wt %, or about 10 wt % of theadditive. For example, the imprint composition contains about 0.01 wt %to about 10 wt %, about 0.01 wt % to about 8 wt %, about 0.01 wt % toabout 5 wt %, about 0.01 wt % to about 4 wt %, about 0.01 wt % to about3 wt %, about 0.01 wt % to about 2 wt %, about 0.01 wt % to about 1 wt%, about 0.01 wt % to about 0.5 wt %, about 0.01 wt % to about 0.1 wt %,about 0.01 wt % to about 0.05 wt %, about 0.1 wt % to about 10 wt %,about 0.1 wt % to about 8 wt %, about 0.1 wt % to about 5 wt %, about0.1 wt % to about 4 wt %, about 0.1 wt % to about 3 wt %, about 0.1 wt %to about 2 wt %, about 0.1 wt % to about 1 wt %, about 0.1 wt % to about0.5 wt %, about 1 wt % to about 10 wt %, about 1 wt % to about 8 wt %,about 1 wt % to about 5 wt %, about 1 wt % to about 4 wt %, about 1 wt %to about 3 wt %, about 1 wt % to about 2 wt %, or about 1 wt % to about1.5 wt % of the additive.

The acrylate can be or include one or more methacrylates, one or moreethylacrylates, one or more propylacrylates, one or more butylacrylates,one or more mono-functional acrylates, one or more di-functionalacrylates, one or more tri-functional acrylates, other multi-functionalacrylates, or any combination thereof. Exemplary acrylates can be orinclude 3-(trimethoxysilyl)propyl methacrylate (3-MPS),3-(trimethoxysilyl)propyl acrylate, di(ethylene glycol) methyl ethermethacrylate, ethylene glycol methyl ether methacrylate, 2-ethylhexylmethacrylate, ethyl methacrylate, hexyl methacrylate, methacrylic acid,vinyl methacrylate, monomers thereof, polymers thereof, salts thereof,complexes thereof, or any combination. In some examples, the acrylate isat a concentration of about 0.05 wt % to about 10 wt %, based on theweight of the nanoparticles.

The imprint composition contains about 0.1 wt %, about 0.2 wt %, about0.3 wt %, about 0.5 wt %, about 0.8 wt %, about 1 wt % to about 1.2 wt%, about 1.5 wt %, about 1.8 wt %, or about 2 wt %, about 2.2 wt %,about 2.3 wt %, about 2.5 wt %, about 2.8 wt %, about 3 wt %, about 3.2wt %, about 3.5 wt %, about 3.8 wt %, about 4 wt %, about 5 wt %, about6 wt %, about 8 wt %, about 10 wt %, about 12 wt %, about 15 wt %, about18 wt %, or about 20 wt % of the acrylate. For example, the imprintcomposition contains about 0.1 wt % to about 20 wt %, about 0.1 wt % toabout 15 wt %, about 0.1 wt % to about 10 wt %, about 0.1 wt % to about8 wt %, about 0.1 wt % to about 5 wt %, about 0.1 wt % to about 4 wt %,about 0.1 wt % to about 3 wt %, about 0.1 wt % to about 2 wt %, about0.1 wt % to about 1 wt %, about 0.1 wt % to about 0.5 wt %, about 1 wt %to about 20 wt %, about 1 wt % to about 15 wt %, about 1 wt % to about10 wt %, about 1 wt % to about 8 wt %, about 1 wt % to about 5 wt %,about 1 wt % to about 4 wt %, about 1 wt % to about 3.5 wt %, about 1 wt% to about 3.2 wt %, about 1 wt % to about 3 wt %, about 1 wt % to about2.8 wt %, about 1 wt % to about 2.5 wt %, about 1 wt % to about 2.3 wt%, about 1 wt % to about 2.2 wt %, about 1 wt % to about 2 wt %, about 1wt % to about 1.8 wt %, about 1 wt % to about 1.5 wt %, about 1.8 wt %to about 20 wt %, about 1.8 wt % to about 15 wt %, about 1.8 wt % toabout 10 wt %, about 1.8 wt % to about 8 wt %, about 1.8 wt % to about 5wt %, about 1.8 wt % to about 4 wt %, about 1.8 wt % to about 3.5 wt %,about 1.8 wt % to about 3.2 wt %, about 1.8 wt % to about 3 wt %, about1.8 wt % to about 2.8 wt %, about 1.8 wt % to about 2.5 wt %, about 1.8wt % to about 2.3 wt %, about 1.8 wt % to about 2.2 wt %, or about 1.8wt % to about 2 wt % of the acrylate.

In one or more examples, the imprint composition contains about 0.5 wt %to about 40 wt % of the nanoparticles, about 50 wt % to about 90 wt % ofone or more solvents, about 5 wt % to about 40 wt % of the surfaceligand, about 0.01 wt % to about 5 wt % of the additive, and about 0.1wt % to about 10 wt % of the acrylate. In other examples, the imprintcomposition contains about 1 wt % to about 25 wt % of the nanoparticles,about 60 wt % to about 85 wt % of one or more solvents, about 6 wt % toabout 35 wt % of the surface ligand, about 0.05 wt % to about 3 wt % ofthe additive, and about 0.3 wt % to about 8 wt % of the acrylate. Insome examples, the imprint composition contains about 5 wt % to about 20wt % of the nanoparticles, about 65 wt % to about 80 wt % of one or moresolvents, about 7 wt % to about 31 wt % of the surface ligand, about0.09 wt % to about 1.5 wt % of the additive, and about 0.5 wt % to about6 wt % of the acrylate.

The imprint composition can have a viscosity of about 1 cP, about 2 cP,about 3 cP, about 5 cP, about 8 cP, or about 10 cP to about 12 cP, about15 cP, about 20 cP, about 25 cP, about 30 cP, about 40 cP, about 50 cP,or about 70 cP. For example, the imprint composition can have aviscosity of about 1 cP to about 70 cP, about 1 cP to about 50 cP, about1 cP to about 40 cP, about 1 cP to about 30 cP, about 1 cP to about 20cP, about 1 cP to about 10 cP, about 1 cP to about 5 cP, about 10 cP toabout 70 cP, about 10 cP to about 50 cP, about 10 cP to about 40 cP,about 10 cP to about 30 cP, about 10 cP to about 20 cP, about 20 cP toabout 70 cP, about 20 cP to about 50 cP, about 20 cP to about 40 cP,about 20 cP to about 30 cP, or about 20 cP to about 25 cP.

In one or more embodiments, the one or more acrylates in the imprintcomposition can be polymerized and/or oligomerized while producing(e.g., curing or otherwise converting) the imprint material, such as theporous nanoimprint film.

Below are several prophetic examples of imprint compositions which canbe produced by embodiments described and discussed herein.

Generic Formulations Concentration Component (wt %) NPs 0.5%-25% surfaceligand 0.5%-20% dispersion solvent  5%-20% acrylate 0.5%-10% imprintingsolvent  60%-80% diol additive 0.5%-8%  surfactant additive 0.01%-1% Total 100

Prophetic Example 1 Concentration Amount Component (wt %) (g) NPs (TiO₂)10% 10 surface ligand  2% 2 PGMEA 12% 12 3-MPS 2.3%  2.3 ethyl lactate71% 71 1,2-propanediol  3% 3 surfactant (FS66) 0.15%  0.15 Total 100 100

Prophetic Example 2 Concentration Amount Component (wt %) (g) NPs (TiO₂)6.5% 6.5 surface ligand 1.5% 1.5 PGMEA  8% 8 3-MPS 2.3% 2.3 ethyllactate  79% 79 1,2-propanediol 2.55%  2.55 surfactant (FS66) 0.15% 0.15 Total 100 100

FIG. 3 depicts a front view of an optical device 300 containing anoptically densified nanoimprint film 306, as depicted in FIG. 2B,according to one or more embodiments described and discussed herein. Inany embodiment described herein, the optically densified nanoimprintfilm 116, as depicted in FIG. 2B, can be the same or used as theoptically densified nanoimprint film 306, as depicted in FIG. 3. It isto be understood that the optical device 300 described below is anexemplary optical device. In one or more embodiments, the optical device300 is a waveguide combiner, such as an augmented reality waveguidecombiner. In other embodiments, the optical device 300 is a flat opticaldevice, such as a metasurface. The optical device 300 includes aplurality of device structures 304. The device structures 304 may benanostructures having sub-micro dimensions, e.g., nano-sized dimensions,such as critical dimensions less than 1 μm. In one or more embodiments,regions of the device structures 304 correspond to one or more gratings302, such as the grating areas 302 a and 302 b. In one or moreembodiments, the optical device 300 includes a first grating area 302 aand a second grating area 302 b and each of the first grating area 302 aand 302 b each contain a plurality of device structures 304.

The depth of the gratings 302 may vary across the grating areas 302 aand 302 b in embodiments described herein. In some embodiments, thedepth of the gratings 302 may vary smoothly over the first grating area302 a and over the second grating area 302 b. In one or more examples,the depth may range from about 10 nm to about 400 nm across one of thegrating areas. The grating area 302 a, in some examples, can range fromapproximately 20 mm to approximately 50 mm on a given side. Therefore,as some examples, the angle of the change in the depth of the gratings302 may be on the order of 0.0005 degrees.

In embodiments described herein, the device structures 304 may becreated using laser ablation. Laser ablation, as used herein, is used toproduce three-dimensional microstructures in the device material, oroptionally to create a variable-depth structure in a sacrificial layeroverlaying the device material as part of a variable-depth structureprocess. Using laser ablation to create the optical structures 304allows for fewer processing operations and higher variable-depthresolution than existing methods.

Embodiments of the present disclosure further relate to any one or moreof the following paragraphs 1-68:

1. A method of forming a nanoimprint film, comprising: positioning asubstrate comprising a porous nanoimprint film within a processingchamber, wherein the porous nanoimprint film comprises nanoparticles andvoids between the nanoparticles, and wherein the porous nanoimprint filmhas a refractive index of less than 2; and depositing a metal oxide onthe porous nanoimprint film and within at least a portion of the voidsto produce an optically densified nanoimprint film during an atomiclayer deposition (ALD) process.

2. The method according to paragraph 1, wherein the metal oxide has arefractive index greater than the refractive index of the porousnanoimprint film.

3. The method according to paragraph 1 or 2, wherein the metal oxide hasa refractive index less than the refractive index of the porousnanoimprint film.

4. The method according to any one of paragraphs 1-3, wherein theoptically densified nanoimprint film has a refractive index greater thanthe refractive index of the porous nanoimprint film.

5. The method according to paragraph 4, wherein the refractive index ofthe optically densified nanoimprint film is about 0.5% to about 30%greater than the refractive index of the porous nanoimprint film.

6. The method according to paragraph 5, wherein the refractive index ofthe optically densified nanoimprint film is about 0.75% to about 10%greater than the refractive index of the porous nanoimprint film.

7. The method according to paragraph 6, wherein the refractive index ofthe optically densified nanoimprint film is about 1% to about 6% greaterthan the refractive index of the porous nanoimprint film.

8. The method according to any one of paragraphs 1-7, wherein therefractive index of the porous nanoimprint film is about 1.5 to about1.95.

9. The method according to any one of paragraphs 1-8, wherein therefractive index of the optically densified nanoimprint film is about1.8 or greater.

10. The method according to any one of paragraphs 1-9, wherein the metaloxide comprises aluminum oxide, titanium oxide, zirconium oxide, niobiumoxide, tantalum oxide, indium oxide, indium tin oxide, hafnium oxide,chromium oxide, scandium oxide, tin oxide, zinc oxide, yttrium oxide,praseodymium oxide, magnesium oxide, silicon oxide, silicon nitride,silicon oxynitride, or any combination thereof.

11. The method according to any one of paragraphs 1-10, wherein thenanoparticles comprise titanium oxide, zirconium oxide, niobium oxide,tantalum oxide, hafnium oxide, chromium oxide, indium tin oxide, siliconnitride, or any combination thereof.

12. The method according to any one of paragraphs 1-11, wherein the ALDprocess comprises sequentially exposing the porous nanoimprint film to ametal precursor and an oxidizing agent during an ALD cycle to depositthe metal oxide.

13. The method according to paragraph 12, wherein the ALD cycle isrepeated from 1 time to about 50 times while depositing the metal oxideduring the ALD process.

14. The method according to any one of paragraphs 1-13, wherein at least3% of the volume occupied by the voids is filled with the metal oxide bythe ALD process.

15. The method according to any one of paragraphs 1-14, wherein about20% to about 90% of the volume occupied by the voids is filled with themetal oxide by the ALD process.

16. A method according to any one of paragraphs 1-15, wherein the porousnanoimprint film is formed on the substrate by an imprint process,comprising: disposing an imprint composition comprising thenanoparticles on the substrate; contacting the imprint composition witha stamp having a pattern; converting the imprint composition to a porousnanoimprint film; and removing the stamp from the porous nanoimprintfilm.

17. The method according to paragraph 16, wherein the imprintcomposition is converted to the porous nanoimprint film by exposing theimprint composition to heat, ultraviolet light, infrared light, visiblelight, microwave radiation, or any combination thereof.

18. The method according to paragraph 16, wherein converting the imprintcomposition to the porous nanoimprint film further comprises exposingthe imprint composition to a light source having a wavelength of about300 nm to about 365 nm.

19. The method according to paragraph 16, wherein converting the imprintcomposition to the porous nanoimprint film further comprises heating theimprint composition to a temperature of about 30° C. to about 100° C.for a time period of about 30 seconds to about 1 hour.

20. The method according to paragraph 16, wherein converting the imprintcomposition to the porous nanoimprint film further comprises heating theimprint composition to a temperature of about 50° C. to about 60° C. fora time period of about 1 minute to about 15 minutes.

21. The method according to paragraph 16, wherein the imprintcomposition is disposed on the substrate by spin coating, drop casting,or blade coating.

22. The method according to paragraph 16, wherein the imprintcomposition is disposed on the substrate as a layer having a thicknessof about 50 nm to about 1,000 nm.

23. The method according to paragraph 16, wherein the imprintcomposition is disposed on the substrate as a layer having a thicknessof about 100 nm to about 400 nm.

24. The method according to paragraph 16, wherein the pattern on thestamp is a 1-dimension pattern, a 2-dimension pattern, or a 3-dimensionpattern.

25. A method of forming a nanoimprint film, comprising: disposing animprint composition comprising nanoparticles on a substrate; contactingthe imprint composition with a stamp having a pattern; converting theimprint composition to a porous nanoimprint film; removing the stampfrom the porous nanoimprint film; positioning the substrate comprisingthe porous nanoimprint film within a processing chamber, wherein theporous nanoimprint film comprises nanoparticles and voids between thenanoparticles, and wherein the porous nanoimprint film has a refractiveindex of less than 2; and depositing a metal oxide on the porousnanoimprint film and within at least a portion of the voids to producean optically densified nanoimprint film during an atomic layerdeposition (ALD) process, wherein the optically densified nanoimprintfilm has a refractive index greater than the refractive index of theporous nanoimprint film.

26. An optically densified nanoimprint film, comprising: a basenanoimprint film comprising nanoparticles and voids between thenanoparticles, and wherein the base nanoimprint film has a refractiveindex of less than 2; and a metal oxide disposed on the base nanoimprintfilm and contained within at least a portion of the voids; wherein theoptically densified nanoimprint film has a refractive index greater thanthe refractive index of the base nanoimprint film.

27. The optically densified nanoimprint film according to paragraph 26,wherein the refractive index of the optically densified nanoimprint filmis about 0.5% to about 30% greater than the refractive index of the basenanoimprint film.

28. The optically densified nanoimprint film according to paragraph 27,wherein the refractive index of the optically densified nanoimprint filmis about 0.75% to about 10% greater than the refractive index of thebase nanoimprint film.

29. The optically densified nanoimprint film according to paragraph 28,wherein the refractive index of the optically densified nanoimprint filmis about 1% to about 6% greater than the refractive index of the basenanoimprint film.

30. The optically densified nanoimprint film according to any one ofparagraphs 26-29, wherein the refractive index of the base nanoimprintfilm is about 1.5 to about 1.95.

31. The optically densified nanoimprint film according to any one ofparagraphs 26-30, wherein the refractive index of the opticallydensified nanoimprint film is about 1.8 to about 2.05.

32. The optically densified nanoimprint film according to any one ofparagraphs 26-31, wherein the metal oxide comprises aluminum oxide,titanium oxide, zirconium oxide, niobium oxide, tantalum oxide, indiumoxide, indium tin oxide, hafnium oxide, chromium oxide, scandium oxide,tin oxide, zinc oxide, yttrium oxide, praseodymium oxide, magnesiumoxide, silicon oxide, silicon nitride, silicon oxynitride, or anycombination thereof.

33. The optically densified nanoimprint film according to any one ofparagraphs 26-32, wherein the nanoparticles comprise titanium oxide,zirconium oxide, niobium oxide, tantalum oxide, hafnium oxide, chromiumoxide, indium tin oxide, silicon nitride, or any combination thereof.

34. The optically densified nanoimprint film according to any one ofparagraphs 26-33, wherein at least 3% of the volume occupied by thevoids in the base nanoimprint film contains the metal oxide.

35. The optically densified nanoimprint film according to any one ofparagraphs 26-34, wherein about 20% to about 90% of the volume occupiedby the voids in the base nanoimprint film contains the metal oxide.

36. An optical device with gratings, comprising: the optically densifiednanoimprint film produced by the method according to any one ofparagraphs 1-25.

37. An optical device with gratings, comprising: the optically densifiednanoimprint film according to any one of paragraphs 26-35.

38. An optical device with gratings, comprising: an optically densifiednanoimprint film, comprising: a base nanoimprint film comprisingnanoparticles and voids between the nanoparticles, and wherein the basenanoimprint film has a refractive index of less than 2; and a metaloxide disposed on the base nanoimprint film and contained within atleast a portion of the voids; wherein the optically densifiednanoimprint film has a refractive index greater than the refractiveindex of the base nanoimprint film.

39. A densified nanoimprint film, comprising: a base nanoimprint filmcomprising nanoparticles, wherein the nanoparticles comprise titaniumoxide, zirconium oxide, niobium oxide, tantalum oxide, hafnium oxide,chromium oxide, indium tin oxide, silicon nitride, or any combinationthereof; and a metal oxide disposed on the base nanoimprint film and inbetween the nanoparticles, wherein the metal oxide comprises aluminumoxide, titanium oxide, zirconium oxide, niobium oxide, tantalum oxide,indium oxide, indium tin oxide, hafnium oxide, chromium oxide, scandiumoxide, tin oxide, zinc oxide, yttrium oxide, praseodymium oxide,magnesium oxide, silicon oxide, silicon nitride, silicon oxynitride, orany combination thereof.

40. The densified nanoimprint film according to paragraph 39, whereinthe base nanoimprint film comprises voids disposed between thenanoparticles, and wherein the metal oxide is disposed at leastpartially within the voids.

41. The densified nanoimprint film according to paragraph 40, wherein atleast 3% of the volume occupied by the voids in the base nanoimprintfilm contains the metal oxide.

42. The densified nanoimprint film according to paragraph 41, whereinabout 20% to about 90% of the volume occupied by the voids in the basenanoimprint film contains the metal oxide.

43. The densified nanoimprint film according to any one of paragraphs39-42, wherein the nanoparticles comprise titanium oxide.

44. The densified nanoimprint film according to paragraph 43, whereinthe metal oxide comprises aluminum oxide.

45. The densified nanoimprint film according to any one of paragraphs39-44, wherein the base nanoimprint film is a film by an imprint processcomprising a spin-coating process, and wherein the metal oxide is acoating deposited by an atomic layer deposition process.

46. The densified nanoimprint film according to any one of paragraphs39-45, wherein the densified nanoimprint film has a greater value ofhardness, fracture strain, yield strength, and/or etch resistance thanthe base nanoimprint film.

47. The densified nanoimprint film according to any one of paragraphs39-46, wherein the densified nanoimprint film has a lesser value ofmodulus of elasticity than the base nanoimprint film.

48. The densified nanoimprint film according to any one of paragraphs39-47, wherein the refractive index of the densified nanoimprint film isabout 0.5% to about 30% greater than the refractive index of the basenanoimprint film.

49. A method of forming a nanoimprint film, comprising: positioning asubstrate comprising a porous nanoimprint film within a processingchamber, wherein the porous nanoimprint film comprises nanoparticles andvoids between the nanoparticles, and wherein the nanoparticles comprisetitanium oxide, zirconium oxide, niobium oxide, tantalum oxide, hafniumoxide, chromium oxide, indium tin oxide, silicon nitride, or anycombination thereof; and depositing a metal oxide on the porousnanoimprint film and within at least a portion of the voids to producean densified nanoimprint film during an atomic layer deposition (ALD)process, wherein the metal oxide comprises aluminum oxide, titaniumoxide, zirconium oxide, niobium oxide, tantalum oxide, indium oxide,indium tin oxide, hafnium oxide, chromium oxide, scandium oxide, tinoxide, zinc oxide, yttrium oxide, praseodymium oxide, magnesium oxide,silicon oxide, silicon nitride, silicon oxynitride, or any combinationthereof.

50. The method according to paragraph 49, wherein the ALD processcomprises sequentially exposing the porous nanoimprint film to a metalprecursor and an oxidizing agent during an ALD cycle to deposit themetal oxide.

51. The method according to paragraph 50, wherein the ALD cycle isrepeated from 2 times to about 50 times while depositing the metal oxideduring the ALD process.

52. The method according to any one of paragraphs 49-51, wherein atleast 3% of the volume occupied by the voids is filled with the metaloxide by the ALD process.

53. The method according to any one of paragraphs 49-52, wherein about20% to about 90% of the volume occupied by the voids is filled with themetal oxide by the ALD process.

54. The method according to any one of paragraphs 49-53, wherein thedensified nanoimprint film has a greater value of hardness, fracturestrain, yield strength, and/or etch resistance than the base nanoimprintfilm.

55. The method according to any one of paragraphs 49-54, wherein thedensified nanoimprint film has a lesser value of modulus of elasticitythan the base nanoimprint film.

56. The method according to any one of paragraphs 49-55, wherein therefractive index of the densified nanoimprint film is about 0.5% toabout 30% greater than the refractive index of the base nanoimprintfilm.

57. A method according to any one of paragraphs 49-56, wherein theporous nanoimprint film is formed on the substrate by an imprintprocess, comprising: disposing an imprint composition comprising thenanoparticles on the substrate; contacting the imprint composition witha stamp having a pattern; converting the imprint composition to a porousnanoimprint film; and removing the stamp from the porous nanoimprintfilm.

58. The method according to paragraph 57, wherein the imprintcomposition is converted to the porous nanoimprint film by exposing theimprint composition to heat, ultraviolet light, infrared light, visiblelight, microwave radiation, or any combination thereof.

59. The method according to paragraph 57, wherein converting the imprintcomposition to the porous nanoimprint film further comprises exposingthe imprint composition to a light source having a wavelength of about300 nm to about 365 nm.

60. The method according to paragraph 57, wherein converting the imprintcomposition to the porous nanoimprint film further comprises heating theimprint composition to a temperature of about 30° C. to about 100° C.for a time period of about 30 seconds to about 1 hour.

61. The method according to paragraph 57, wherein converting the imprintcomposition to the porous nanoimprint film further comprises heating theimprint composition to a temperature of about 50° C. to about 60° C. fora time period of about 1 minute to about 15 minutes.

62. The method according to paragraph 57, wherein the imprintcomposition is disposed on the substrate by spin coating, drop casting,or blade coating.

63. The method according to paragraph 57, wherein the imprintcomposition is disposed on the substrate as a layer having a thicknessof about 50 nm to about 1,000 nm.

64. The method according to paragraph 57, wherein the imprintcomposition is disposed on the substrate as a layer having a thicknessof about 100 nm to about 400 nm.

65. The method according to paragraph 57, wherein the pattern on thestamp is a 1-dimension pattern, a 2-dimension pattern, or a 3-dimensionpattern.

66. An optical device with gratings, comprising: the densifiednanoimprint film according to any one of paragraphs 39-48.

67. An optical device with gratings, comprising: the densifiednanoimprint film produced by the method according to any one ofparagraphs 49-65.

68. An optical device with gratings, comprising: a densified nanoimprintfilm, comprising: a base nanoimprint film comprising nanoparticles,wherein the nanoparticles comprise titanium oxide, zirconium oxide,niobium oxide, tantalum oxide, hafnium oxide, chromium oxide, indium tinoxide, silicon nitride, or any combination thereof; and a metal oxidedisposed on the base nanoimprint film and in between the nanoparticles,wherein the metal oxide comprises aluminum oxide, titanium oxide,zirconium oxide, niobium oxide, tantalum oxide, indium oxide, indium tinoxide, hafnium oxide, chromium oxide, scandium oxide, tin oxide, zincoxide, yttrium oxide, praseodymium oxide, magnesium oxide, siliconoxide, silicon nitride, silicon oxynitride, or any combination thereof.

While the foregoing is directed to embodiments of the disclosure, otherand further embodiments may be devised without departing from the basicscope thereof, and the scope thereof is determined by the claims thatfollow. All documents described herein are incorporated by referenceherein, including any priority documents and/or testing procedures tothe extent they are not inconsistent with this text. As is apparent fromthe foregoing general description and the specific embodiments, whileforms of the present disclosure have been illustrated and described,various modifications can be made without departing from the spirit andscope of the present disclosure. Accordingly, it is not intended thatthe present disclosure be limited thereby. Likewise, the term“comprising” is considered synonymous with the term “including” forpurposes of United States law. Likewise, whenever a composition, anelement, or a group of elements is preceded with the transitional phrase“comprising”, it is understood that the same composition or group ofelements with transitional phrases “consisting essentially of”,“consisting of”, “selected from the group of consisting of”, or “is”preceding the recitation of the composition, element, or elements andvice versa, are contemplated.

Certain embodiments and features have been described using a set ofnumerical upper limits and a set of numerical lower limits. It should beappreciated that ranges including the combination of any two values,e.g., the combination of any lower value with any upper value, thecombination of any two lower values, and/or the combination of any twoupper values are contemplated unless otherwise indicated. Certain lowerlimits, upper limits and ranges appear in one or more claims below.

What is claimed is:
 1. A method of forming a nanoimprint film,comprising: positioning a substrate comprising a porous nanoimprint filmwithin a processing chamber, wherein the porous nanoimprint filmcomprises nanoparticles and voids between the nanoparticles, and whereinthe porous nanoimprint film has a refractive index of less than 2; anddepositing a metal oxide on the porous nanoimprint film and within atleast a portion of the voids to produce an optically densifiednanoimprint film during an atomic layer deposition (ALD) process.
 2. Themethod of claim 1, wherein the metal oxide has a refractive indexgreater than the refractive index of the porous nanoimprint film.
 3. Themethod of claim 1, wherein the metal oxide has a refractive index lessthan the refractive index of the porous nanoimprint film.
 4. The methodof claim 1, wherein the optically densified nanoimprint film has arefractive index greater than the refractive index of the porousnanoimprint film.
 5. The method of claim 4, wherein the refractive indexof the optically densified nanoimprint film is about 0.5% to about 30%greater than the refractive index of the porous nanoimprint film.
 6. Themethod of claim 5, wherein the refractive index of the opticallydensified nanoimprint film is about 1% to about 6% greater than therefractive index of the porous nanoimprint film.
 7. The method of claim1, wherein the refractive index of the porous nanoimprint film is about1.5 to about 1.95.
 8. The method of claim 1, wherein the refractiveindex of the optically densified nanoimprint film is about 1.8 orgreater.
 9. The method of claim 1, wherein the metal oxide comprisesaluminum oxide, titanium oxide, zirconium oxide, niobium oxide, tantalumoxide, indium oxide, indium tin oxide, hafnium oxide, chromium oxide,scandium oxide, tin oxide, zinc oxide, yttrium oxide, praseodymiumoxide, magnesium oxide, silicon oxide, silicon nitride, siliconoxynitride, or any combination thereof.
 10. The method of claim 1,wherein the nanoparticles comprise titanium oxide, zirconium oxide,niobium oxide, tantalum oxide, hafnium oxide, chromium oxide, indium tinoxide, silicon nitride, or any combination thereof.
 11. The method ofclaim 1, wherein the ALD process comprises sequentially exposing theporous nanoimprint film to a metal precursor and an oxidizing agentduring an ALD cycle to deposit the metal oxide.
 12. The method of claim11, wherein the ALD cycle is repeated from 1 time to about 50 timeswhile depositing the metal oxide during the ALD process.
 13. The methodof claim 1, wherein about 20% to about 90% of the volume occupied by thevoids is filled with the metal oxide by the ALD process.
 14. A method ofclaim 1, wherein the porous nanoimprint film is formed on the substrateby an imprint process, comprising: disposing an imprint compositioncomprising the nanoparticles on the substrate; contacting the imprintcomposition with a stamp having a pattern; converting the imprintcomposition to a porous nanoimprint film; and removing the stamp fromthe porous nanoimprint film.
 15. The method of claim 14, wherein theimprint composition is converted to the porous nanoimprint film byexposing the imprint composition to heat, ultraviolet light, infraredlight, visible light, microwave radiation, or any combination thereof.16. The method of claim 14, wherein converting the imprint compositionto the porous nanoimprint film further comprises exposing the imprintcomposition to a light source having a wavelength of about 300 nm toabout 365 nm.
 17. The method of claim 14, wherein converting the imprintcomposition to the porous nanoimprint film further comprises heating theimprint composition to a temperature of about 30° C. to about 100° C.for a time period of about 30 seconds to about 1 hour.
 18. A method offorming a nanoimprint film, comprising: disposing an imprint compositioncomprising nanoparticles on a substrate; contacting the imprintcomposition with a stamp having a pattern; converting the imprintcomposition to a porous nanoimprint film; removing the stamp from theporous nanoimprint film; positioning the substrate comprising the porousnanoimprint film within a processing chamber, wherein the porousnanoimprint film comprises nanoparticles and voids between thenanoparticles, and wherein the porous nanoimprint film has a refractiveindex of less than 2; and depositing a metal oxide on the porousnanoimprint film and within at least a portion of the voids to producean optically densified nanoimprint film during an atomic layerdeposition (ALD) process, wherein the optically densified nanoimprintfilm has a refractive index greater than the refractive index of theporous nanoimprint film.
 19. An optically densified nanoimprint film,comprising: a base nanoimprint film comprising nanoparticles and voidsbetween the nanoparticles, and wherein the base nanoimprint film has arefractive index of less than 2; and a metal oxide disposed on the basenanoimprint film and contained within at least a portion of the voids;wherein the optically densified nanoimprint film has a refractive indexgreater than the refractive index of the base nanoimprint film; whereinabout 20% to about 90% of the volume occupied by the voids in the basenanoimprint film contains the metal oxide; and wherein the refractiveindex of the optically densified nanoimprint film is about 1 to about 6%greater than the refractive index of the base nanoimprint film.
 20. Theoptically densified nanoimprint film of claim 19, wherein: the metaloxide comprises aluminum oxide, titanium oxide, zirconium oxide, niobiumoxide, tantalum oxide, indium oxide, indium tin oxide, hafnium oxide,chromium oxide, scandium oxide, tin oxide, zinc oxide, yttrium oxide,praseodymium oxide, magnesium oxide, silicon oxide, silicon nitride,silicon oxynitride, or any combination thereof; the nanoparticlescomprise titanium oxide, zirconium oxide, niobium oxide, tantalum oxide,hafnium oxide, chromium oxide, indium tin oxide, silicon nitride, or anycombination thereof; the refractive index of the base nanoimprint filmis about 1.5 to about 1.95; and the refractive index of the opticallydensified nanoimprint film is about 1.8 to about 2.05.